LIGHT FIDELITY

BYGagana M (MCA 4th sem)

NandiniT R (MCA 4th sem)

Dayananda Sagar College Of Arts Science And Commerce

Li-Fi is the transmission of data throughillumination by taking the fiber out of fiberoptics by sending data through a LED lightbulb.

This varies in intensity faster than human eyecan follow.

It is the fast and cheap wirelesscommunication system which is optical whichis optical version of the Wi-Fi.

•THIS TECHNOLOGY WASINVENTED BY GERMAN

PHYSICIST HARALD HAAS , FROM

THE UNIVERSITY OF EDINBURGH ,U.K .

• HE DEMONSTRATED IT IN THE YEAR2012.

1.4 Million 5 Billion

•Radio Spectrum is congested but the demand for wireless data double each year .Every thing, it seems want to use wireless data but the capacity is drying up.

•So what can carry this excess demand in the future.

•Drawbacks - Capacity, Availability, Security & Efficiency.

Li-Fi has a High speed

data transfer rate over

1Gbps.

LI-FI USES THE

VISBLE LIGHT

PORTION OF THE EM

Wi-Fi has a data transfer

rate of maximum 54Mbps.

WIFI USE THE

RADIOWAVE

PORTION OF THE EM

Radio Waves

Infrared Rays

Visible Rays

Ultraviolet Rays

X- Rays Gama Rays

Gama rays cant be used as they could be

dangerous.

X-rays have similar health issues.

Ultraviolet light is good for place without

people, but other wise dangerous for the

human body.

Infrared, due to eye safety regulation, can

only bse used with low power.

Its working is much simply explained as follows: If the LED is on, the digital 1 is transmitted. And if it is off, the digital 0 is transmitted. It is possible to encode data in the light by

varying the rate at which the LEDs flicker on andoff to give different strings of 1s and 0s.

Li-Fi product consists of 4 primary sub-assemblies: Bulb RF power amplifier circuit (PA) Printed Circuit Board (PCB) Enclosure

3-The PCB controls the electrical inputs and outputs of the lamp and

houses the microcontroller used to manage different lamp functions.

2- An RF (radio-frequency) signal is generated by the solid-state PA and

is guided into an electric field about the bulb. The high concentration of

energy in the electric field vaporizes the contents of the bulb to a plasma

state at the bulb’s center; this controlled pasma generates an intense

source of light. All of these subassemblies are contained in an aluminum

enclosure.

1.TRAFFIC LIGHTS

3-AirlinesWhenever we travel through airways we face the problem in communicationmedia ,because the whole airways communication are performed on the basisof radio waves. To overcomes this drawback on radioways , li-fi is introduced.

4-INTRINSICALLY SAFE ENVIRONMENT

Visible Light is more safe than RF, hence it can be used in places where RF can't be used such as petrochemical plants .

5-ON OCEAN BEDS

Li-Fi can even wok underwater were Wi-Fi fails completely, thereby throwing open endless opportunities for military/navigation operations.

CAPACITY

WITH THE ADVENT OF NEW TECHNOLOGIES LIKE 3G ,4G WE ARE RUNNING OUT OF SPECTRUM.

THAT’S WHY RADIO WAVES ARE NOW BECOMING EXPENSIVE.

EFFICIENCY

THERE ARE 1.4 MILLIONS CELLULAR RADIO BASE STATIONS .

EFFICIECY OF EACH BASE STATION IS JUST 5%.

MOST OF THE ENERGY IS NOT USED FOR TRANSMISSION BUT RATHER FOR COOLING DOWN THE BASE STATION.

SECURITY RADIO WAVES CAN PENETRATE

THROUGH WALLS AND HENCE CAN BE INTERCEPTED.

ANYONE WITH KNOWLEDGE AND BAD INTENTION CAN MISUSE IT.

AVALILABLITY WE HAVE TO SWITCH OFF MOBILES IN

AIRCRAFTS. IT IS ALSO NOT ADVISABLE TO USE

MOBILES AT PETROL PUMPS.

Presence of light is essential There should be line of sight Works better with fluorescent light and

LEDs but very low efficiency with bulbs

Higher speeds than Wi-Fi. 10000 times the frequency spectrum of radio. More secure because data cannot be intercepted

without a clear line of sight. Prevents piggy backing. Eliminates neighboring network interference. Unimpeded by radio interference. Does not create interference in sensitive

electronics, making it better for use in environments like hospitals and aircraft.

By using LiFi in all the lights in and around a building, the technology could enable greater area of coverage than a single Wi Fi router.

Limitations 0r challenges-

• light can't pass through objects

•Interferences from external light sources like sun light, normal bulbs, and opaque materials in the path of transmission will cause interruption in the communication.

•High installation cost of the VLC systems

•A major challenge facing Li-Fi is how the receiving device will transmit back to transmitter.

The possibilities are numerous and can be explored further. If this technology can be put into practical use , every bulb can be used something like a Wi-Fi hotspots to transmit wireless data.